environment + technology

Dean Kamen’s Stirling Solution

photos: green wombat
In a world of Stepford executives who never deviate from the corporate party line, there’s something refreshing about an entrepreneur willing to take a tumble – literally – for his latest innovation. In uber-inventor Dean Kamen’s case that meant crashing his Stirling electric hybrid scooter in front of Green Wombat and a photographer. In June, Green Wombat visited Westwind, Kamen’s estate outside Manchester, New Hampshire, to talk to the Segway inventor about his plans to install a Stirling heat engine in an electric car made by Norway’s Think. (See "Have You Driven a Fjord Lately?" in the August issue of Business 2.0.) But first, Kamen wanted to demo the scooter (photo above) to show how a virtually greenhouse gas-free Stirling engine could extend the range of an electric vehicle by trickle-charging the battery. As he zooms down the driveway, the scooter goes sideways – its weight distribution needs some tweaking – sending the inventor flying into the grass. "Say you’re in Bangladesh or anywhere in the world where people don’t have electricity," says Kamen, dusting himself off and not missing a beat. "You get home and you plug your house into it." He shows off power plugs behind the scooter’s seat. "It’s your power system, it’s your heating system, it gives everybody electricity. When you leave in the morning, you drive away with your local power plant."

Over the past decade, Kamen, who made a fortune as inventor of the insulin pump and other medical devices, has spent some $40 million developing Stirling engines. They can use virtually any fuel source to heat a sealed container containing a gas – hydrogen or helium, for instance – that expands and contracts to drive a piston and produce electricity. (The scooter uses a small can of propane as the fuel source.) "We run two villages in Bangladesh on Stirlings that run on freakin’ cow dung," says Kamen, who envisions Stirling engines powering the world’s off-the-grid villages and using the waste heat produced by the engine to purify water.

But Kamen needs to get to mass production to realize that dream and that’s where Think comes in. Kamen met Think CEO Jan-Olaf Willums last year at MIT. "I took him up to New Hampshire and we spent half the night speculating about how cool the world could be if you put the right technologies in the right place at the right time," says Kamen. "I need some killer app to put this thing into production. And one way to do that would be to create the world’s first hybrid Stirling electric car." So Willums shipped a Think City to Kamen, who is now modifying the two-seater coupe to carry a Stirling engine (photo at right) powered by veggie oil, for instance. ("You could drive across the country, stopping a McDonald’s to fill up," says Kamen.) That would not only extend the Thinks range by hundreds of miles but turn the car into a mobile generator. When electricity demand peaks during the day, thousands of Thinks plugged in at office parks could feed power back to the grid so utilities like PG&E (PCG) and Edison (EIX) could avoid having to fire up planet-warming power plants. The Stirling engine would then recharge the car’s battery for the commute home. When we last spoke in July, Kamen had the autmotive version of the Stirling engine up and running. The next step is to hook it up to the City and see if it’ll work as planned. You probably won’t see a Stirling in a Toyota (TM) or Ford (F) but the device gives Think another power plant to offer its customers.

“If you have enough Thinks out there you would literally change the architecture of the grid,” says Kamen, taking Green Wombat for a drive around Westwind and past his wind turbine before parking the blue Think City near his pair of Enstrom helicopters. (He keeps the Think in a garage that also houses his 1898 steam-driven car and a 1913 Model T.) Kamen heads to the control room of his 33,000-square foot house. An Internet-enabled blue box called a Teletrol controls the home’s power systems, including a Stirling engine about the size of an air conditioner that can act as a backup generator or a mini power plant that kicks on when electricity demand soars. Kamen invented the Teletrol and his company of the same name remotely operates the heating and air-conditioning systems of buildings like the Sydney Opera House. Kamen, of course, would like to see a Teletrol in every house, acting as the interface between your Web-enabled Think and the grid (and, ideally, the Stirling engine that sits in your basement or utility room.)

"The big advantage is once we’re in production with that engine, where it will really be uniquely valuable is to the 1.6 billion people on this plant who’ve never used electricity," says Kamen. "We will become the Con Edison of every village in Asia, Africa and Central America."

Like this:

LikeLoading...

Related

21 Responses

That sounds so awesome. I live up in Alaska, USA and while most the cities have fairly dependable power a lot of the bush communities don’t. If the Stirling engine is scalable so that it could be put into 4 wheelers or even mid sized boats it could really change the face of power consumption my state and probably the whole world.

I’m very curious about its efficiency and the mechanism it uses to accomplish this.

There were a lot of rumors about the segway before its release and really it was an interesting idea, just one that a lot of pepole didn’t see as a needed thing. This Stirling solution has all the trappings of becoming a world wide phenomena.

=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
Great article, I wish there was a little more technical info about how the whole system works, but I’m sure that will come available eventually. I’d love to see you do an article on Plasma Gasification in regards to dealing with our dump/garbage issues. It’s another one of those ideas that has a lot of potential, almost to the point where you start asking “Okay, it all sounds too good to be true, so whats the catch?”

Yep this is the big lie. The Stirling engine which is 200 years old is an external combustion engine. This means it runs on heat from an external source. Where is Kamen getting his heat? from the sun? No from fuel or electricity which generate green house gases. He has been working on this for around 7 years as I read about this here in silicon valley at that time when Doeer was touting this and the Ginger/Segway as earth shattering inventions. Save your money. Other companies including BMW are already talking about harvesting the waste heat from their engines to improve efficiency.

It does indeed generate power the dirty old fashioned way, but the point is about efficiency. A million local generators are way more efficient than 1 big one in a remote location, and the efficiency gain directly translates to a reduction in overall power generation, energy costs and carbon emissions.
Snarf.

As another Alaskan, I am also interested in this technology. Anywhere in the bush where they burn wood or coal for heat in the winter could use heat/stack-robbers to power the Stirlings. Much of the state’s northern coast from about Nome is bereft of natural fuels. Many communities rely on very expensive fuel oil for surviving the -60 winters. Stirling engines could possibly off-set some of these costs.

Just a correction, it’s not a Teletrol but an eNC built by Teletrol, a company that Dean bought to make building automation equipment. I use to work there and wrote a lot of the code that runs in the eNC.

And to respond to KillJoy, a Stirling Engine only needs a temperature differential to run. You could use fossil fuels but sunlight from a solar collector would work just as well…

Looks like the sterling engine is not quite generating power the old fasioned way . . . according to this link . . .http://www.stirlingenergy.com/whatisastirlingengine.htm . . . for those not inclined to click through . . “The gasses used inside a Stirling engine never leave the engine. There are no exhaust valves that vent high-pressure gasses, as in a gasoline or diesel engine, and there are no explosions taking place. Because of this, Stirling engines are very quiet. The Stirling cycle uses an external heat source, which could be anything from gasoline to solar energy to the heat produced by decaying plants. No combustion takes place inside the cylinders of the engine.”

The Stirling engine (in a PHEV, which is what we’re talking about making) is definitely better, and indeed is a paradigm shift away from pollution, but global warming isn’t the main point. You can also run ICE engines off of biofuels, although the Stirling should be more efficient and is much more friendly to a wide range of convenient, safe biofuels. But the big difference is that the Stirling decimates the temptation to emit local pollution (including noise). It is so many times easier to burn clean with a simple continuous burner that, well, steam cars from the 1920’s still meet today’s pollution regulations. Smog is an ICE/petroleum partnership-caused problem. And once you’ve taken away the profits to be made in driving people to heavy polluting (due to the high costs of clean), we’ll stop fighting over it and just end the reign of smog.

The promise of the Stirling engine is a lot like the promise of the fuel cell, except that it uses (spruced-up) technology from decades ago instead of decades from now. The biggest obstacles to popular Stirling cars were long warm-up time, and somewhat lower power density, but now in the era of PHEVs (and heavy smog gear requirements) neither matters anymore.

Begs a huge question completely unanswered by this article: WHAT FUEL IS THIS THINK/STIRLING CAR GOING TO BE BURNING?

Cow dung? What?

Stirling engines are wonderful and intriguing. I would love to have one. I hope Kamen is really making some improvements because the power to weight ratio of other modern Stirlings is still so abysmal that they are far too heavy to put in a vehicle. So you are not going to be able to run the City continuously, the Stirling will not be able to keep up. It will only be able to extend the driving range, and be able to recharge while parked without plugging in.

But even granting that, you’re still burning fuel of some kind to power them. Surely you are not going to be feeding cow dung into your Think City? And without some kind of huge solar ray collection mirror or something, the car is not going to be solar powered.

I can still see another advantage being that it might be extremely flexible on the type of fuel burnt. It ought to be very easy to burn whatever is handy from gasoline to diesel to ethanol to methanol etc.

The Toyota Prius already achieves high efficiencies while producing essentially no noise and tiny amounts of smog. Is the Stirling hybrid’s efficiency going to be better than an advanced ICE hybrid? How is this better than a Toyota system, and how much better?

Kamen is definitely a brilliant guy, but he’s not beyond a hare-brained idea or two. The Segway hasn’t exactly revolutionized transportation as he claimed. Truth be told, I would wager he has lost millions on the Segway.

If the Stirling runs on temperature difference would not the heated interior of a vehicle during the summer be enough. My understanding is that vehicle interiors get well above 100 degrees. Should it not also work in the winter, when the interior of the car is either colder or warmer than the outside temperature?
As for the whole light bulb thing, CF lightbulbs are taking off because they are cheap, equal to or better in lumens, last forever, and use a quarter of the energy of an incandescent bulb. People will always switch to something that makes life better, if some SOB does not buy it up and put it on the shelf.

Also, would not a heat sink of the stirling engine connected to BEV lithium battery packs result in recovered electrical energy while at the same time removing unwanted heat that can reduce battery efficiency and even cause damage if temp specs are exceeded?

There’s only so much total energy in any temperature differential, and that’s going to be the limitation with any Stirling power solution. Sure, you might be able to get reasonable power output if you park a solar collector next to your house, or burn cow dung in a village somewhere, but the total energy contained in a car parked in an open parking lot pales in comparison to the energy needed to drive that car home in the afternoon.

High efficiency is no match for the basic physics of moving a one or two thousand pound vehicle down the road, even with reasonably low coefficients of drag.

The electric motors in a hybrid vehicle, such as the Prius (when my current gasoline-mobile has reached end-of-life, there’s a Camry in my future, so I’m more familiar with that platform), consumes many horsepower, each of which comes at a 745 watt pricetag and yields 550 lb-feet / second. There are only so many watts available per square meter coming down from the sun, and by the time the sun’s energy makes it to the ground, it is no where near the 1,365 or so watts it is up above the atmosphere. The laws of thermodynamics are not suspended just because one wishes to use a Stirling engine.

As other commenters pointed out, fossil fuel is needed to provide the heat source for a Stirling equipped vehicle. So it is not “virtually green house gas-free” as the article said.

There is also a bit of a safety issue when you have external combustion in a moving vehicle. That can be addressed, but it’s more of a concern than an internal combustion engine. Parking your car in the garage where you might have some leaky cans of paint thinner filling the room with fumes all day might result in an unhappy event. Pulling up to the pump at a gas station could be particularly exciting.

A Stirling engine can run on a pretty small temperature differential but you won’t get much power out of it. You need a very large temperature differential for high efficiency and lots of power. The temperature differential between the interior of a vehicle and the outside won’t get you far, and there’s an insignificant amount of heat energy in that small volume of air anyway.

If you pay attention to what is said in the article, the car is not powered by the Stirling engine. It is an electric car, and the engine is used to recharge the battery and extend its capacity. In addition to external combustion heat sources, it can recapture heat generated by the battery and braking among. It’s not a zero emission system, it’s a reduced-emission system.

Kamen is an incredibly creative, intelligent individual. Everything he’s done (including the Segway) has been technologically groundbreaking. He’s not some crackpot who thinks he can break the laws of physics with his perpetual motion machine; he wouldn’t be spending the money he is on this project if he didn’t know it can work. Whether it will be economically successful is a different question, but I would never bet against Kamen on anything technological. If he says it’s possible, it’s possible.

Add an Ultra clean Low-Swirl injector (LSI)burner to heat the Stirling engine and away you go. It would make a clean efficient low emission solution. I wonder if the low swirl injector technology could be made to work with liquid fuels like gasoline? Then you would have your killer application for vehicles.

try to buy a sterling engine, say about 3 to 5
horsepower. I cannot find one for sale to use as a power generator for my cabin, located in 100 aacres of trees.
There are lots of claims about the sterling engines but I have only seen toy models for sale.

About Green Wombat

Green Wombat is written by
Todd Woody, a veteran environmental journalist based in California who writes for The New York Times, the Los Angeles Times, Grist and Yale e360. He's one of the few people on the planet who have held a northern hairy-nosed wombat in the wild.

Todd formerly was a senior editor at Fortune magazine, an assistant managing editor at Business 2.0 magazine and the business editor of the San Jose Mercury News.